Method of making a liner bag



April 2, 1963 J. G. VERGOBB] METHOD OF MAKING A LINER BAG 2 Sheets-Sheet 1 IN V EN TOR.

Filed Jan. 30, 1961 0 0 g 6% V v 0 0 0mm. an

ATTORNEY April 2, 1953 J. G. VERGOBBI 3,083,618

METHOD OF MAKING A LINER BAG Filed Jan. 30, 1961 2 Sheets-Sheet 2 ATTORNEY United States Patent Ofiice Patented Apr. 2, 1%63 This invention relates to a method of making a liner bag for a package.

The invention has for an object to provide a novel and improved method of making a liner bag having an overlapping side seam and a folded bottom closure wherein novel revision is made for sealing the side seam and the bottom closure in a manner such as to produce a leakproof and airtight bag.

With this general object in View and such others as may hereinafter appear, the invention consists in the method of making a liner bag as hereinafter described and particularly defined in the claim at the end of this specification.

In the drawings illustrating the preferred embodiment of the invention:

FIG. 1 is a perspective View illustrating a sheet of liner bag forming material wrapped about a forming block and provided with a longitudinal overlapping side seam heat sealed to form a tubular structure;

FIG. 2 is a similar view showing the extended portions of the tube being folded to provide a bottom closure;

FIG. 3 is an end view showing the completely folded bottom closure;

FIGS. 4 and 5 are similar views of the folded bottom closure showing the preferred sealing pattern employed to produce a leakproof bottom closure;

FIG. 6 is an enlarged cross sectional view of the heat sealed side seam taken on the line 66 of FIG. 2;

FIGS. 7 and 8 are enlarged cross sectional views of the ."folded bottom closure as taken on the lines 7--7 of PEG. 4 and 8--8 of FIG. 5, respectively, and showing the heat sealed portions of the bottom closure;

FIG. 9 is a perspective View of an outer bag wrapped about the forming block and the liner bag; and

FIG. 10 is a perspective view showing the completely lined bag.

In general the present invention contemplates a novel and improved method of making a liner bag for a package wherein the liner bag may comprise a relatively thin thermoplastic sheet material, such as Pliofilm, preferably transparent, and capable of being heat sealed by the application of heat and pressure to overlapping portions thereof. In the illustrated embodiment of the invention the thermoplastic sheet material is wrapped about a forming block with the longitudinal marginal edges of the sheet arranged in overlapping relation, such marginal edges being sealed together along relatively narrow spaced lines by the application of heat and relatively slight pressure to form a tube. A portion of the tube extends beyond the outer end of the forming block for forming the bottom closure, and opposed walls or" such extended portion are folded inwardly against the bottom of the block in overlapping relation. Each inwardly folded wall of the extended portion forms a tapering or trapezoidal shaped flap connected by triangular shaped gussetlike folds which overlie the first folded flaps and underlie the last folded flaps. In accordance with the present invention the folded and overlapping portions of the bottom closure are heat sealed along predetermined spaced lines in a novel pattern such as to provide an airtight bottom closure.

The present liner bag is adapted to be produced on a high speed packaging machine, known in the trade as a double package maker, wherein the liner bag is formed by wrapping the sheet about the forming block and sealing the overlapping portions of the side seam at one station of operation; folding and sealing the bottom closure at a second station of operation; wrapping an outer bag or carton about the forming block and its liner bag and sealing the side seam of the outer at a subsequent station; and folding and sealing the bottom closure of the outer bag at another station, the completed lined bag or package being then stripped from the forming block ready to be filled and provided with a top closure.

Referring now to the drawings, 19 represents a relatively thin sheet of flexible thermoplastic or other thermoresponsive liner bag material, overlapping portions of which are capable of being fused together upon the application of heat and relatively slight pressure. In producing the bag, as shown in FIG. 1, the liner sheet 16 may be wrapped about a horizontally extended forming block 12 to form an elongated tubular structure rectangular in cross section, the longitudinal marginal edges 14, 1601' the sheet being brought together in overlapping relation and sealed along two relatively narrow spaced lines 18, 29 by the application of heat and pressure to provide a longitudinally extended double line side seam disposed substantially medially of the side walls of the tube, as indicated at 22. In practice the double line seam 22 may be produced by an elongated heat sealing bar 24, as shown in FIG. 6, provided with two spaced relatively narrow elongated sealing projections or ridges l9 and 21 and which cooperate with a resilient portion of the forming block which may comprise an insert 26 of rubberlike material capable of withstanding heat. The heat sealing operation effects softening and flowing together of the thermoplastic material of the overlapping portions to form the fused or welded line seals 18, 20. In practice the sealing ridges of the bar 2 and the cooperating resilient insert 26 in the forming block 12 may be coated with a suitable antistick material to prevent sticking of the softened material to the sealing elements.

During the operation of wrapping the liner sheet about the forming block, opposed folding elements 28, 3d are operated in sequence to :fold the mar inal portions of the sheet across the upper surface of the horizontally extended block in a manner such as to arrange the marginal portions in overlapping relation, and in operation the folding elements 28, 3% remain at rest in the position shown in FIG. 6 to retain the edges of the sheet in overlapping relation during the heat sealing operation. It will be observed that the liner sheet 19 extends beyond the outer end of the block to provide extended wall portions for forming the bottom closure at a subsequent station or" operation. It will also be observed that the double line side seam 22 extends to the outer end of the forming block, the side seam terminating substantially at the corner of the block at the point indicated at 32, leaving the overlapping portions 34 of the extended wall free or unsealed. However, in operation the sealing bar 24 extends a short distance beyond the end of the block so that in practice the side seam seal extends a short distance beyond the end of the corner of the block.

Thereafter, the opposed walls of the extended end Wall portions of the tube are folded inwardly against the end of the forming block in overlapping relation in a predetermined sequence to form the bottom closure as illustrated in FIGS. 2 and 3. In practice the upper and lower extended end walls are first folded inwardly simultaneously against the end of the forming block by suitable folding elements to provide tapering or trapezoidal shaped flaps 36, 38, respectively. Then, the remaining opposed extended end walls are folded inwardly against the end of the forming block by suitable folding elements to lik seal at the corner portion 32 of the forming block.

wise provide tapering or trapezoidal shaped flaps 40, 42, respectively, the first folded flaps 36, 38 being connected to the last folded flaps 40, 42 by triangular shaped gussetlike folds-43 which overlie the first folded flaps and underlie the last folded flaps as illustrated. It will be observed that the ends of the first folded flaps are spaced apart in the completed bottom fold, and the last folded flaps are folded in a sequence such that the end of the flap 42 overlaps a portion of the end of -the flap 40 as shown.

It will be observed that the tapering flaps and the gussetl-ike connecting portions are open at their outer ends and that the last folded flaps 40, 42 overlie portions of the first folded flaps 36, 38. Accordingly, the pattern of heat sealing the bottom closure preferably contemplates the provision of at double line heat seal across each flap to seal the overlapping portions of the flaps together andto close off any passageway through which air may leak between the open ends and overlapping portions of the flaps whereby to produce an airtight and leakproof bottom closure for the bag.

As illustrated in FIGS. 4 and 7, the overlapping end portions of the flaps 40, 42 are sealed to each other and to portions of the underlying flaps 36, 38 by a vertical double line heat seal along lines 44, 46 closing the open endsof the flaps 40, 42 and also closing the remainder or extended portion 34 of the overlapping side seam which occurs in the bottom closure- As illustrated in FIG. 7, the vertical end or bottom closure seal lines 44, 46 are produced by a heat sealing bar- 48 having two spaced and relatively narrow sealing ridges 45 and 47 which cooperate with a resilient portion 50 of rubberlike material inserted in the end of the forming block. The vertical seal lines 44, 46 are coextensive with the side seam seal lines 18, 20, and in practice the sealing bar 48 may extend a short distance beyond the upper surface of the forming block so that the upper ends of the seal lines 44, 46 overlap the extended ends of the seal lines 18, 20 a short distance to assure a continuous side seam It will be observed that the seal lines 44, 46 terminate short of the lower end of the block at a point 49 immediately beyond the overlapping ends of the flaps 40, 42 as shown.

It will also be observed that the cross section shown in FIG. 7 is taken at a point wherein five plies of the thermoplastic material are heat sealed together comprising the flaps 40, 42, the connecting gusset portions 43 for each flap and the underlying lower flap 38. It will also be observed that the vertical double line heat seal is performed while the folding elements indicated at 52, 54 are at rest to retain the flaps in their folded condition during the sealing operation. The heat sealing operation effects fusion of the thermoplastic material along the lines 44, 46 to produce airtight seals as indicated in FIG. 7.

From the description thus far it will be seen that the liner bag is provided with a heat sealed side seam and a vertical bottom closure 'heat seal to continue the side seam along the extended portion 34 thereof and to seal minate inwardly of the sides of the block. In other words the transverse seal lines are continued across the multiply portions of the end closure and terminate when they reach the single ply portion thereof as shown. It will be observed that the transverse seal lines intersect the vertical seal lines 44, 46.

As illustrated in FIG. 8, the transverse seals may be produced by a sealing pad 64 having a pair of upper sealing ridges 65, 66 and a pair of lower sealing ridges 67, 68 which also cooperate with the resilient insert 50 provided in the end of the block. The transverse sealing operation also serves to fuse the multi-ply layers of the bottom closure together to produce air-tight seals 7 closing off any leakage between the flaps 36, 38 and the overlying portions of the closure. As seen in FIG. 8, the cross section is taken at a point wherein the upper transverse seal fuses together the underlying flap 36, in-

' termediate gusset portion 43 and overlying flap 42, and

the lower transverse seal fuses together the underlying flap 38, intermediate gusset portion 43 and the overlying flap 42.

It will be seen that the folded and sealed bottom closure thus defined provides an airtight and leakproof seal, each seal comprising a double line seal bonding or welding together the multi-ply portions in an area intermediate sealed areas or lines because a greater concentration of heat may be applied along the narrow lines to quickly fuse the overlapping plies together, and while the sealing 1 elements are provided with an antistick coating it has the open endsof the last folded flaps 40, 42 to each other 7 and to the underlying portions of the first folded flaps 36, 38 to thus seal the bottom closure fiom any leakage which might otherwise occur between the folded flaps 40, 42 and the underlying flaps and between the overlapping portions of the side seam extension 34. Thereafter, at a'subsequent station of operation, two double line transverse heat sealing seams or lines are applied to the'bottom closure, as shown in FIG. .5, in a pattern such as to seal the open ends of the first folded flaps 36, 38 to the overlying portions of the flaps 40, 42. As herein shown, the uppertransverse seam. is formed by spaced seal lines 56, 58 which extend across an area defined by the underlying flap 36 and terminate inwardly of the sides of the block. Likewise, the lower transverse seam is formed by spaced seal lines 60, 62 which extend across an area defined by the underlying flap 38 and also terbeen found that more difiiculty is encountered in preventing sticking of the softened thermoplastic material.

to wider sealing elements. Also, a relatively wide heat seal is more subject to the formation of air bubbles between the overlapping plies such as to form imperfect seals. Since more uniform contact between the sealing element and material may be attained with a narrow sealing element air bubbles between the plies are eliminated, and the use of a double line seal further assures an airtight seal.

While'reference is made herein to first folded flaps and last folded flaps, when describing the formation of the bottom closure, in practice the flaps are folded concurrently from four sides during the initial portion of the folding operation, the first folding elements being retracted before the second folding elements to complete their operation, and the latter being moved in a sequence such as to effect overlapping of the end of one flap with the end of the other. Also, in practice the second folding elements 52, 54 come to rest in spaced relation to retain. all of the flaps in their folded condition during the vertical line heat sealing operation whereupon they are fully retracted.

'After completion of the liner'bag bottom closure an outer sheet 70 of bag material may be wrapped about the forming block and the bag carried thereby, and the overlapping marginal portions of the sheet are adhesivel-y sealed together to provide a side seam as indicated at 72, in FIG. 9. The extended portions of the bag material machine where the product to be packaged is deposited in the lined bag.

The filled bag may then be provided with a top closure in any usual or preferred manner to provide an airtight top closure seal. The illustrated lined bag shows the top or mouth of the liner bag flush with the top or mouth of the outer bag, and in practice this type of bag is adapted to be provided with a bellows or gusset type fold and heat sealed by the application of heat and pressure to seal the contacting mouth portions of the thermoplastic liner bag in airtight relation. A modified type of top closure may include a line seal across the flattened mouth of the thermoplastic liner bag. It will be understood that the present liner bag may also be used with advantage as a liner in other types of packages, such as a liner for a carton provided with the usual adhesively secured top and bottom closure flaps.

The illustrated package when provided with a Pliofilm liner bag having airtight seals, as described, is particularly adapted for use as a container for ground coffee. One of the known characteristics of the Pliofilm material is that it 'has some degree of porosity. Thus, any increase in pressure within the sealed liner bag caused by gas generated by the coffee may slowly escape through the bag material, and such pressure within the bag will prevent air from the atmosphere from entering the bag, thus maintaining the coffee in fresh condition. However, the present invention also contemplates bags made from other materials which may be non-porous and when sealed as described will provide a hermetically sealed container.

While in the foregoing description the liner bag has been described as formed from a sheet of thermoplastic or thermoresponsive material it will be understood that other sheet materials may be used, and such materials coated in the predetermined areas to be sealed with heat and/or pressure sensitive adhesives such that the liner bag may be sealed along the predetermined seal lines as herein described.

While the preferred embodiment of the invention has been herein illustrated and described, it will be understood that the invention may be embodied in other forms within the scope of the following claim.

Having thus described the invention, what is claimed The method of producing a liner bag which comprises the steps of folding a rectangular sheet of thermoplastic bag forming material about a rigid forming block having resilient portions with the longitudinal marginal edges of the material in overlapping relation to form a rectangular tube with one end of the tube extended beyond the end of the forming block, applying heat and relatively Slight pressure along two spaced relatively narrow lines to the overlapping marginal edges in cooperation with the resilient portions of the block to provide a fused airtight side seam extending from the inner end of the tube to a point slightly beyond the outer end of the block leaving the remainder of the extended overlapping side seam portions unsealed in the partially completed bag, folding opposed end walls of the extended end of the tube inwardly against the end of the block to provide a bottom fold having trapezoidal shaped flaps and having portions in overlapping relation and connected by intervening triangular gusset folds forming multi-ply portions, the ends of the last folded flaps arranged in overlapping relation, applying heat and relatively slight pressure along two relatively narrow spaced lines parallel to the outer ends of said last folded flaps in cooperation with the resilient portions of the block to fuse said flaps together and to the underlying portions of the first folded opposed flaps and the gusset folds in airtight relation, said parallel spaced lines terminating a short distance beyond the multi-ply portions of the bottom fold, then applying heat and relatively slight pressure along two pairs of relatively narrow spaced lines simultaneously in cooperation with said resilient portions, said pairs of spaced lines being arranged intermediate the ends of each of said first folded flaps and intersecting the lines sealing the first folded flaps to fuse the latter to the overlying last folded flaps and the gusset folds in airtight relation to provide an airtight bottom closure, one pair of said spaced lines being coextensive with the extended portions of said side seam seal lines, said two pairs of narrow seal lines also terminating a short distance beyond the multi-ply portions of the bottom fold.

Moore Feb. 13, 1940 Harvey May 19, 1953 

